| From: | Ben Chobot <bench(at)silentmedia(dot)com> |
|---|---|
| To: | "Joshua D(dot) Drake" <jd(at)commandprompt(dot)com> |
| Cc: | pgsql-general(at)postgresql(dot)org |
| Subject: | Re: Maximum transaction rate |
| Date: | 2009-03-13 18:41:53 |
| Message-ID: | Pine.LNX.4.64.0903131139560.10022@localhost.localdomain |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-general |
On Fri, 13 Mar 2009, Joshua D. Drake wrote:
>> It seems to me that all you get with a BBU-enabled card is the ability to
>> get burts of writes out of the OS faster. So you still have the problem,
>> it's just less like to be encountered.
>
> A BBU controller is about more than that. It is also supposed to be
> about data integrity. The ability to have unexpected outages and have
> the drives stay consistent because the controller remembers the state
> (if that is a reasonable way to put it).
Of course. But if you can't reliably flush the OS buffers (because, say,
you're using LVM so fsync() doesn't work), then you can't say what
actually has made it to the safety of the raid card.
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